1. Field of the Invention
The present invention relates to a consecutive taking camera for taking plural consecutive exposures. More particularly, the present invention relates to a consecutive taking camera of which a shutter device is improved in compact fashion.
2. Description Related to the Prior Art
There is a lens-fitted photo film unit as a single-use camera disclosed in U.S. Pat. Nos. 4,884,087 and 4,972,649. It has a main body, which incorporates a taking lens, a one-frame advance mechanism and a shutter mechanism. The rear of the main body is pre-loaded with 135 film with a cassette in a factory, and covered with a rear cover in light-tight fashion. The front of the main body is covered with a front cover. An operable film-winding wheel is externally rotated after effecting each exposure, to wind the photo film into the cassette. After taking all exposures on the film, the photo film unit is forwarded to a photo laboratory where the film is developed so as to produce photo prints.
There are variants of photo film units for various uses: a flash built-in type, a telephoto type and a close-up type. Besides, there is a camera with plural lenses for taking consecutive exposures, for the purpose of photography of a moving subject in fashion of a set of still photographs taken successively at short intervals: such as a moving form of a sportsman.
There are proposals of a consecutive taking camera: in a first proposal, four consecutive sub-frames are taken within a single frame of the 35 mm full size (24.times.36 mm) in two rows and two columns; in a second proposal, eight consecutive sub-frames are taken within horizontally arranged two frames of panoramic size (13.times.36 mm), where each panoramic frame is provided with four sub-frames, as disclosed in U.S. Pat. No. 5,210,557; and in a third proposal, four sub-frames are taken in one row, as suggested in commonly assigned co-pending patent application Ser. No. 08/186,119.
Another proposal of a consecutive taking camera is disclosed in JP-A 5-45697, in which eight consecutive sub-frames are taken in two rows and four columns, with the intention of convenience in apparent recognition of the order in the sub-frames. Eight stationary openings with a fixed aperture stop are arranged in a 2.times.4 matrix. A shutter device is incorporated, and includes four shutter disks, which have each rotational axis equally distant from two adjacent ones of stationary openings arranged in the direction of moving the film. Each of the four shutter disks is provided with two slits, which are formed in positions at different radii from the rotational axis. The shutter disks are rotated by a motor, to move the slits past the stationary openings time-sequentially for effecting consecutive exposures.
For still photography of a moving subject such as a sportsman, a slit formed in a shutter disk should be moved past a stationary opening at exposure time of at shortest 1/125 second. If rotation of the shutter disk is excessively fast, a consecutive duration from the beginning to the end of plural exposures may be too short, so that the fast rotation may be unsuitable for covering an apparent motion of the photographic subject. If rotation of the shutter disk is excessively slow, the duration of the whole sequence may be too long, so that the slow rotation may be likely to cause over-exposure on the film, and may be unsuitable for covering the fast motion of the photographic subject. The above disclosed shutter device, in view of the situation, is driven by use of a motor, which is controlled by a controller to rotate at a greater speed only during each of the exposures.
However, there is a shortcoming in the consecutive taking shutter device with the motor-driven shutter disk. A camera with the shutter device is highly costly, and requires spaces for containing a battery and a printed circuit board as well as the motor. The motor-driven shutter device is inconsistent to a lens-fitted photo film unit, which should be compact and inexpensive as compared with a camera in general.
The photo film unit has the one-frame advance mechanism as above. An operation of winding the film rotates a driven sprocket wheel. The one-frame advance mechanism responds to an end of advancement of the film as far as one frame, and stops the sprocket wheel and the winding wheel from being rotated even if the winding wheel is pressed rotationally. At the moment of the release of the shutter device, the sprocket wheel and the winding wheel are enabled to rotate.
The operation of photography in a consecutive taking camera requires a duration longer than operation of photography in a simple type of photo film unit for a single exposure, because the latter effects a plurality of exposures upon a single releasing operation. There occurs a problem if the above one-frame advance mechanism is incorporated in a consecutive taking camera: the winding wheel and the sprocket wheel are unlocked immediately upon the triggering of the shutter, so that the winding wheel becomes rotatable before the end of the plural exposures. If the winding wheel is moved at all during some of the plural exposures, the film is inadvertently moved even during the exposure to cause blurs on subject images in sub-frames.